The proposed research is concerned with the synthesis of thio and selenosugar esters of dialkylarsinous acid. These will have the basic formula GSAsR2 and GSeAsR2 where G is the sugar moiety and R is an alkyl group. During the next year the laboratory effort will be directed as follows. The synthesis of a group of derivatives in which G is 6-thio-beta-D-glucopyranose and R is varied to include several esters in which the alkyl group has a chain of 16 or 17 carbon atoms will be attempted. It will be of interest to prepare derivatives in which other functional groups which show biological activity in addition to the dialkylarsino group are incorporated in the molecule. Consequently, it is planned to synthesize dialkylarsinous acid esters of-5-thio-beta-D-glucose and 2-amino-beta-D-glucose.